So-called non-returnable packages for, for example, beverages or similar liquid foodstuffs are usually manufactured from plastics-coated paper or similar packing laminate which by means of conventional folding and sealing operations can be formed to parallelepipedic packing containers. Such a known parallelepipedic container is TetraBrik (registered trade-mark) which on its top side may have a prepared emptying opening, preferably placed adjoining a corner edge, with a pouring tab facilitating the emptying of the contents projecting over the container edge in connection with the emptying opening. The emptying opening and the pouring tab are preferably covered by a strip as an openable seal to the top side of the container and which with its front end (gripping tab) extends over the container edge all around the projecting pouring tab. Packing containers of the type described here are known, for example, from DK patent specification No. 136 811, U.S. Pat. No. 4,126,263 and EP No. A2 0 001 134. DE OS No. 2 758 092 also describes a similar packing container. When such a container is to be emptied of its contents, the seal of the strip against the upper side of the container is broken by pulling the strip with the help of the gripping tab upwards and backwards over the emptying opening which consequently is exposed.
The packing container described has a series of substantial advantages both in respect of manufacture and from a point of view of application. It is simple, inexpensive and easy to manufacture in fast-operating packing machines and offers flexible possibilities of distribution and storage. It has, moreover, good handling characteristics and allows the emptying of the contents in a well-concentrated and easily directable jet. In glaring contrast to these advantages, however, appears the imperfect facility of the container for reclosure of the emptying opening once exposed, which, of course, is particularly serious in cases where the container is large and holds more contents then the amount required for use just at the moment and therefore requires a tolerably "safe" storage of the contents between occasions of emptying.
Reclosing cover strips for container openings are certainly known in themselves and generally some type of adhesive coating is used on the side which faces the container opening. Such sticky cover strips function well in cases where the container material is sufficiently resistant to tearing so as not to tear off and attach itself to the sticky surface when the cover strip is pulled off. Not much success has been achieved, on the other hand, using these cover strips with packing material of the type consisting of paper with thin plastic coatings, but the use here has been limited to container material of sheet metal, aluminium etc. which is especially resistant to tearing.
Reclosable cover strips of the "press fastener type" have also been tried, but this type too makes demands on the mechanical strength of the container material and is less well suitable, therefore, for relatively easily deformable material as represented by packing laminate of the type consisting of paper with thin plastic coatings.